System and apparatus for enhancing convection in electrolytes to achieve improved electrodeposition of copper and other non ferrous metals in industrial electrolytic cells

ABSTRACT

A system and apparatus for enhancing convection in electrolytes for improved electrodeposition of copper and other non ferrous metals in industrial electrolytic cells at given a current density providing exact geometric locations of the electrolyte jet infeed supply system used to impart forced convection in the electrolyte, the gas bubbling system for low pressure/low volume convection enhancement, and the electrode bottom and lateral distancing system, and range of operational parameters, for correct electrolyte flow and air bubbling flow improving cell productivity, quality of metal plates with increased electrical efficiency for its industrial application. The system and apparatus can also be used in industrial cells with same optimal results but at increased current densities, provided sufficient suitable electrolyte and additional electric power is available.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application of U.S. ProvisionalPatent Application No. 61/096,394 filed on Sep. 12, 2008, the entiretyof which is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was not federally sponsored.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to the general field of aqueous electrolyticelectrodeposition, and more specifically toward a system and apparatusfor enhancing convection in electrolytes to achieve improvedelectrodeposition of copper and other non ferrous metals in industrialelectrolytic cells at industrial scale operations. The system andapparatus are useful in both electrowinning and electrorefining versionsof electrodeposition.

Industrial electrodeposition of metals as practiced today is one of themost complex unit operations known due to the unusually large number ofcritical elementary related phenomena or process steps which control—andindeed determine—the success of the overall process. The nature of thesecomplex phenomena ranges from physico-chemical through electrochemicalto the purely electrical, and they interact simultaneously at distancesfrom the electrode surfaces that range from an atomic radius to anelectrode spacing in the cells.

Electrowinning is also the oldest industrial electrolytic process.Reportedly first demonstrated experimentally by von Leuchtenberg in1747, the process was used by H. Davy to produce metallic potassium andsodium in a lab in 1807. The first commercial process for silver platingwas developed by Siemens and patented by Elkington in 1865, and thefirst copper electrolytic refinery was built in New Jersey in 1883 tosupport the booming growth of telegraph and telephone wires. Large scaleindustrial electrowinning from leached copper oxides, as we know ittoday, was first developed in 1915 at Chuquicamata, Chile.

Substantial evolution has taken place in electrodeposition industrialplants in the last 100 years resulting from the constant efforts tosubstitute manual labor by mechanization, automation and processcontrols with technology. More recently, efficiency improvements inmaterials handling automation and safety in plant and equipmentoperation have been introduced, driven by the substantially improvedperformance and durability achieved by new anti-corrosive structuralpolymer composite materials.

By and large, however, the productivity and energy efficiency of theindustrial process still remains poor mainly due to inefficientelectrodes and inadequate functional arrangements of equipment insideelectrolytic cells, which explains the moderate current densities usedand overall insufficient process control that keep plant sizes large andmetal inventory excessive. Notwithstanding, advances inhydrometallurgical recovery rates of metal ions by solvent extractionfrom leached low grade ores are more environmentally friendly, andeconomic electrolytes in recent years have boosted cost effectivenessand acceptance of the process in new mega size mining projects andentrepreneurial size mining ventures alike. Similar technologyelectrolytic cells are used at present in projects of all sizes, so thebenefits of the system and apparatus of the present invention areespecially adaptable to the needs of any existing industrialelectrolytic cell regardless of plant capacity, whether new or alreadyin operation. Increased productivity and quality with improved energyefficiency processes are highly desirable for a number of reasons andmandatory from a business sustainability perspective in the XXI Century.

The foregoing descriptions of shortcomings of the present art ofelectrodeposition refer to the copper electrowinning process, but areequally applicable to copper electrorefining process, and generically,to all electrorefining processes of non ferrous metals.

In the present art copper electrowinning industrial practice, currentdensities (typically in an average range of 250 to 350 amperes/m2) areapplied to the electrodes in electrolytic cells to deposit high qualityplates of copper (substantially complying with LME standards such asBS6017, ASTM B115, etc.) on the cathodes from given flows of varyingcomposition electrolytes containing copper ions in acid solutionsobtained by respective solvent extractions from suitably leached copperores. In connection with the foregoing, the term “current density” isthe ratio of direct electric current, expressed in amperes, to thesurface area of cathodes in the electrolytic cells, expressed in squaremeters. In a more recent established copper electrowinning practice, theelectrolytes are pressure jet fed from strategic locations into theinterleaved anode-cathode spaces in the electrolytic cell fromhorizontal feed pipes generally pointing towards the interelectrodespaces, installed on the lower vertices of the side walls of the cellnear the bottom, to create a suitable “forced” convection of theelectrolyte relative to the surfaces of the energized electrodes, thatcan be adjusted to sustain other process variables in equilibrium toconsistently deposit satisfactory physical, chemical and metallographicquality metal with acceptable productivity and current efficiency intime. A fundamental fact in this present practice of the art is thatelectrodeposition productivity is directly proportional to the currentdensity, and accordingly, the long-sought ultimate goal is to run theprocess at maximum current density for maximum metal yield. However, awell established dictum supported by long-held practical experienceholds that the maximum sustained current density to operate a givenindustrial plant in time—given its specific process technology,equipment, electrolyte chemical composition, additives, power andoperational experience available—is that which allows it to successfullymaintain process electrochemical and physico-chemical and the vitalelectrical variables substantially in stable equilibrium, thus enablingto steadily yield the desired quality of metal electrodeposition overtime. One of the main obstacles preventing those skilled in the art fromincreasing the present art current density levels from presentlyachieved equilibriums is the lack of an electrolyte convection enhancingsystem tailored for the specific constraints of present art industrialelectrolytic cells, that when implemented will provide a stable andreliable process, thus enabling operators to sustain the newsuccessfully adjusted process variables in time at their new stableequilibriums to meet the quality of metal deposit objectives with thenew increased current density.

The system and apparatus of the present invention are directed towardsspecifically enhancing the effects of convection in the electrolyteimparted by a pressure feed system in a state-of-the-art industrialcopper electrowinning cell operating at a given current density, whichis designed to provide a given “specific flow ratio” of electrolyte of agiven composition to the total energized cathode surface area in thecell, expressed in cubic meters of electrolyte flow per hour per squaremeter of energized cathode surface. Said enhancement of convection isproperly implemented, as proposed in this invention, by means of a lowpressure, low volume gas diffusion system with suitable adjustments ofthe gas flow relative to the specific flow and should directly result ina first level of stable improvement in the quality of electrodeposit andin the electrical efficiency of the cell when the gas enhancement systemis connected and correctly adjusted. Further, such enhancement ofconvection, generally maintaining the initial given specific flow,usually suffices to also allow increasing the initial current density inthe industrial cell to a certain incremental level without detriment tothe quality of electrodeposition while at the same time minimizing theincremental consumption of electric power. Essentially, in order toaccomplish the above goals, the system and apparatus provided will needto first fix precisely the relative positions of both the existingelectrolyte infeed system operating with its predetermined flow anddischarge paths of the electrolyte relative to the electrode surfaces inthe existing cell and the convection enhancement system speciallytailored relative to the electrodes and the cell with its predeterminedgas diffusers for given favorable bubbling sizes and discharge patterns.Then, the system and apparatus will need to incorporate thecontributions of a low pressure, low volume gas diffusion in favorablesize and patterns of bubbles from the convection enhancement systemoperating and positioned in a horizontal plane below and across thevertical faces of the electrodes with predetermined volume and pressureof gas for establishing such favorable bubbling sizes and dischargepatterns. The enhancement effect occurs in the bottom-to-surfacedirection on the overall electrolyte convection in the interelectrodespaces, and is most generally effective if preferably guided laterallywith strategic vertical convection baffles installed on the anodes of anelectrode distancing system, to positively enhance and guide upwardconvection constricted in the interelectrode spaces that gently anduniformly sweeps across the entire electrode surfaces. This ispreferably accomplished while positively maintaining the cathodes attheir predetermined spacing from the anodes and also while maintainingthem simultaneously insulated from each other at all times. A majorbenefit to be derived from the application of the complete system andapparatus of this invention is a significant reduction or elimination ofelectrical short circuits due to contacts between energized anodes andcathodes. This preventive feature not only reduces the need of dedicatedamounts of tedious “systems work” in industrial practice to locate andcorrect electrical malfunctions and short circuits, but also increasesproductivity, deposit quality, and current efficiency as well as “wearand tear” of costly electrodes and electrical bus bars. In fact, takingcare of “systems work” is an everyday problem in large electrowinningplants, some of which have 66,000 cathodes or more under current at anygiven time. For reference, if only half of one percent of the cathodesare in or near short circuit, it means 330 cathodes scattered throughthe huge electrowinning plant need urgent attention, representing amajor yet inevitable problem to the uniform success of the massiveelectrowinning process. Improvements in current efficiency have becomean imperative with increasing electrical power costs and growingscarcity of competent specialized labor.

A novelty of the present invention is in teaching exactly how theconcatenation of the correctly designed and specified three subsystemsoperate interlinked as one holistic effective system to improveelectrodeposition that can be implemented with present day practices inexisting as well as in new industrial electrolytic cells, and furthersuccessfully coordinated for overall synergies adding up theirindividual contributions to increased quality and productivity. Somegood ideas from past art have been salvaged, practically modified toeliminate short comings, and then placed in an effective holisticcontext, which is the novel strategy in which this invention helps tostably achieve the most favorable results or outcomes at industrialscale from the electrodeposition process at today's practical currentdensities, considering, of course, mandatory constraints in labor,environment and competitiveness of present (2008) industrialelectrowinning plant operating practices. These primary goals orbenefits are: increased productivity, better quality deposits—smooth andvirtually free of porosity throughout all stages of growth from startuntil harvest—and higher current efficiency. Further, once these primarygoals are achieved or substantially improved using the invention, sincethe benefits of the enhanced convection levels provided herein includesubstantially diminishing the present limiting diffusion layers of theelectrolyte at the electrodes, the electrodeposition process using thesame existing equipment, labor and operational practices can also becontinuously run at higher current densities (providing sufficientvolumes of satisfactory electrolytes and direct electric current can bemade available efficiently) and doing so will, in turn, yield yetadditional increased productivity and current efficiency, whileretaining the characteristic high quality metal deposits.

To begin, U.S. Pat. No. 684,049 discloses, as early as 1901, anelectrode distancing system with a toggle mechanism inside the cellmanually operated from the outside, (Note: labor intensive system) forpositive distancing of energized anodes and cathodes at theirpredetermined spacing inside electrolytic cells of a copper refinery inorder to prevent ever present short circuits; and similarly, U.S. Pat.No. 1,397,735, of 1921, shows another electrode spacing concept usinghorizontal runners vertically slotted at the electrode spacing attachedon the inner upper longitudinal edges of the lateral cell walls forpositive permanent placement and vertically straight positioning of theelectrodes in an electrolytic cell for coal recovery by a separationprocess.

Further, U.S. Pat. No. 1,260,830, of 1918, discloses an electrolyticprocess for ionic deposition of copper from acid solutions providingcontinuous agitation of the electrolyte, particularly across the face ofthe anodes, with a mixture of sulfur dioxide gas and steam sparged fromnozzles in lead tubes—forming a transverse network of pipes permanentlymounted at the bottom of the cell—(Note: cluttering the cell bottom withpiping makes it difficult to clean anode slime periodically) tostrategically impinge at favorable angles on the faces of anodes tomaximize agitation across the respective face surfaces.

Another example is U.S. Pat. No. 3,928,152, of 1975, describing a methodfor improved electrolyte convection in copper electrowinning basedprimarily—and only—on air sparging, using bubbler tubes placed parallelto each cathode face at their lower edge, while the cathode-anodeinterspaces are diminished but positively distanced, and alsoconveniently enshrouded laterally with baffles to restrict the ascendingflow of air bubbles within the space defined between the electrodes as ameans to further enhance the beneficial effects air sparging bysubstantially directing the gas bubbling to the surfaces of the cathodes(Note: air bubbling as a stand alone means of convection enhancement incopper electrowinning is impractical because it requires verysubstantial volumes of sparging air resulting in significant turbulentflow of the electrolyte at the cathode surfaces compromising the purposeof uniform deposition quality; moreover, such increased air volumesadding to the normal volume of emission of acid mist, and utilizingcomplex structures made of non durable thermoplastic that clutter cellbottoms, make cells difficult to clean; air feeding to and control incell are not disclosed).

Similarly, U.S. Pat. No. 4,263,120, of 1981, proposes transverseindividual air bubbling devices attached to the lower edges of theanodes discharging curtains of air bubbles whose ascent is restrictedwithin the interelectrode spaces formed by very closely spaced cathodesconfined laterally by vertical insulator/spacer baffles mounted on bothlateral edges of the anodes. (Note: relative volumes of electrolyte feedwith sparging air feed to the cell are not resolved).

Similarly, U.S. Pat. No. 3,959,112, of 1976, describes the use oftubular air sparging elements cooperatively associated with each cathodeon both opposing faces placed at their lower edges with air emerging asa uniform curtain of fine bubbles sweeping the plating surfaces of thecathode to substantially inhibiting the formation of rough surfacedeposits (Note: air feed and control to the sparging system notdisclosed, correct positioning, attachment to the cell and connection tothe air source not disclosed, cell bottom cleaning with air spargingsystem installed not disclosed).

More recently, U.S. Pat. No. 6,849,172 B2 of 2005, describesintroduction of fresh electrolyte under pressure through jets mixed withsparging gas through a mixing nozzle from a combined feed systemdischarging in predetermined directions into the cell (Note: thepressurized jet infeed of electrolyte upon mixing with air preempts anydiscrete contributions of air bubbling by itself to the electrolyte) andPCT—WO2005/019502 A1 of March 2005, proposes a gas sparging system usingpredetermined volumes of low pressure air saturated with water vapor(Note: bringing air saturated with water into the sparging system insidethe industrial cell eventually makes the water vapor in the air condensein the system, clogging it for air and the system turns into a watersparger into the cell, and/or adding substantial amounts of water intothe electrolyte which is objectionable). The water saturated air isdelivered from a manifold installed inside the cell (Note: manifolddescription is not disclosed in detail but description does mention theconstruction material is PVC pipe to which the hoses are attached, whichis absolutely unsuitable structurally for the application because theywill not hold the desired position) and the manifold is connected tomicroporous hoses “which can be easily replaced” (Note: how this isaccomplished is not disclosed).

Finally, U.S. Pat. No. 3,483,568 of 1969, and U.S. Pat. No. 4,098,668 of1978, disclose the merits of forced feeding of electrolyte directed todischarge from the bottom of the cell into the interspaces of individualanode-cathode pairs—while U.S. Pat. No. 5,492,608 of 1996, proposessimilar forced discharge directed from the side walls—and all coincidingwith the resulting positive effectiveness of forced feeding to controlplated metal quality and purity even from electrolytes containing highconcentrations of undesirable ions, which reportedly, thanks to theforced convection, do not deposit as impurities on the copper plate.

SUMMARY OF THE INVENTION

The current invention provides just such a solution by having a systemand apparatus for enhancing convection in electrolytes to achieveimproved electrodeposition of copper and other non ferrous metals inindustrial electrolytic cells at a given current density providing exactgeometric locations of the electrolyte infeed system, especially wherepressure infeed systems are deemed necessary to impart forced convectionin the electrolyte, and the gas diffusion system for low pressure/lowvolume convection enhancement with adequate given favorable bubblingsizes and discharge patterns and the electrode bottom and lateraldistancing system, and range of operational effective parameters, forcorrect electrolyte flow and air diffusion flow improving cellproductivity, quality of metal plates with increased electricalefficiency for its industrial application. The system and apparatus canalso be used in industrial cells with same optimal results atincrementally increased current densities, provided sufficient suitableelectrolyte and additional electric power are available.

It can be concluded by the foregoing patent analysis that thetechnological solutions proposed in the various patents did not succeedin making their way into industry as innovations, principally becauseone or more necessary aspects or details deemed necessary to suitconditions for sustained success of the complex electrodepositionprocess in industrial scale electrolytic cells were simply omitted, weretechnically vague, uncertain and/or weak, simply incorrect, resultsreported deemed exaggerated, experimental, or not demonstrated validlyat industrial scale, etc. Whatever the reasons, the fact remains thatpoor reception of enhanced electrolyte convection as an innovation bythe industry have rendered the various partial solutions claimed eitherimpractical or outright not viable for large scale operations. Unlikethe prior art, the current invention provides a complex system correctlydesigned to efficiently and effectively enhance convection inelectrolytes for improved electrodeposition of copper and other nonferrous metals in industrial electrolytic cells.

The present invention recognizes the present shortcomings of industrialpractice and provides a global system for enhancing convection ofelectrolyte in industrial cells, specially aimed to industrialelectrolytic cells used for copper electrowinning—and with suitableadaptations, also in cells for electrorefining of copper—focusingprimarily on the strategy of effective characterization, monitoring andprocess control of final quality of metal plates harvested, and alsotheir deposition growth in the cathodes, with simultaneous high currentefficiency. The system proposed as one unit is formed by threesubsystems wherein the first subsystem is an electrolyte infeed supplysystem for a given specific flow and composition, balanced for a givencurrent density, which is provided in the case of copper electrowinningdescribed herein preferably through dual manifold tubes installedhorizontal and longitudinally along the lower vertices of the lateralwalls near the cell bottom, with oriented perforations of givendiameters in the piping for controlled pressure jetting electrolyte—inopposite predetermined paths—towards the interelectrode spaces providinga basic forced convection in the industrial cell. The first subsystemcan be operated simultaneously interlinked with any one of the other twosubsystems or preferably both (low pressure, low volume gas bubbling andpositive spacing of electrodes and protection of gas bubbling systeminside the cell). The specific object in copper electrowinning disclosedherein is enhancing the basic forced convection of the electrolytegenerally provided by an electrolyte jet infeed subsystem, preferablylocated at each lower corner of the flat surfaces of the cathodes in aneffective manner to achieve improved electric efficiency and qualityelectrodeposition of copper in industrial cells. Optimal results inproductivity, quality of copper plates, and process current efficiencyare obtained while operating simultaneously with all three subsystemslinked together (concatenated), geometrically precisely installedrelative to each other and exactly positioned with respect to theelectrolytic cell in which they operate so they can be effectively andefficiently interlinked to produce the results sought.

The improvement of the art provided by this invention is multiple.First, the construction and installation of the equipment described ispractical, validated for industrial scale operations and achieved byusing only well-proven, durable and stable polymer composite materialsspecified for the ultra heavy duty of full immersion service in acidelectrolytes. Second, providing the exact geometrical positioning of thethree subsystems inside any existing—or new—industrial electrolytic cellthat will allow effective adjustment of current density withpredetermined volume flows of the fluids involved in favorable dischargepaths to achieve the precise enhancement of the basic convection ofelectrolyte infeed uniformly sustained at the plating surfaces, whilealso promoting uniform distribution of metal ion concentration in thebulk electrolyte for a given set current density. Third, based on theevaluation of electrodeposition results of harvested metal platesshowing stability and merits for attempting to increase also theproductivity of the process, increase current density in incrementalsteps by functional fine tuning adjustments of the predetermined jettingof electrolyte infeed at favorable locations and paths under theelectrodes with the corresponding correct low pressure, low volume flowof gas forming the required patterns of uniform and stable diffused gasbubbles sweeping the plating surfaces at the predetermined spacing ofcathodic mother plates or permanent cathode blanks, until attaining theresults expected, thereby the process variables functionally adjusted tomaintain a stable process from the beginning of metal deposition throughthe end of each production cycle in the electrolytic cell. Fourth, forpractical industrial operation, all three subsystems provided arereadily displaced out of the way from their concatenated respectiveworking positions when the industrial cell is periodically emptied forinspection, removal of anode slimes and cleaning its bottom. This is animportant practical problem for the operation of industrial electrolyticcells that has remained as an unresolved practical obstacle until thisinvention.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are additional features of theinvention that will be described hereinafter and which will form thesubject matter of the claims appended hereto. The features listed hereinand other features, aspects and advantages of the present invention willbecome better understood with reference to the followingdescription—exemplified by but not restricted to industrialelectrowinning of copper—and appended claims. The accompanying drawings,which are incorporated in and constitute part of this specification,illustrate embodiments of the invention in industrial electrowinning ofcopper and, together with the description, serve to explain the genericprinciples of the invention in industrial electrowinning andelectrorefining of copper, and electrodeposition processes of nonferrous metals.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and togetherwith the description, serve to explain the principles of this invention.

FIG. 1 shows a system detail inside a generic industrial electrolyticcell (1) with the three subsystems correctly installed in relation toeach other attached in positioning structure (2) for simultaneousconcatenated operation according to the invention to enhance convectionof the electrolyte (100) and thus accrue the benefits claimed ofincreased quality and productivity of electrodeposited metal with highercurrent efficiency at a given current density.

FIG. 2 shows a cross section of generic electrowinning electrolytic cell(1) looking towards the discharge end of the industrial cell which showsan anode (13) hanging vertically inside cell (1) correctly positionedand held distanced from the adjacent cathodes (not shown) by thepyramids (12) of the positive distancing subsystem (10), and alsorelative to both the convection enhancing subsystem (6) shown in itshorizontal working position (B) and the electrolyte forced infeed systemwith infeed manifolds at positions (5)—shown in working positionpressure jetting electrolyte through orifices (5B)—or alternate manifoldposition (100). Manifolds (5) are shown with electrolyte (100)discharging from orifices (5B) in predetermined paths towards theelectrode interspaces above forming forced convection flow pattern (100a) with the enhanced convection contributed by controlled discharge oflow pressure air micro bubbles emerging from appropriate diffusers orpresent art microporous hoses (9) held in predetermined positions byholders (8) attached to self supporting reticulated structure (6) of theconvection enhancing subsystem.

FIG. 3 is a cross section of generic industrial cell (1) looking towardsthe electrolyte infeed end of the cell with electrodes removed from cell(1) showing the electrolyte down corner infeed pipe (5 a) pressurefeeding electrolyte (shutdown) to the horizontal jet manifolddistribution pipes (5) (or alternate position (50)), and the convectionenhancing sub system (6) (shut down) is shown abated 110° from itsworking position (A) and passed its vertical position resting on thelateral cell wall in (B) completely out of the way, allowing free accessinside the of cell (1) of an operator for removing anodic slimeperiodically from the cell bottom. Flexible hose (4A) feedspredetermined volumes of low pressure external air to the convectionenhancing system (6)

FIG. 4 is a top view of generic industrial electrolytic cell (1) withelectrodes removed to show the three subsystems installed complete, andcorrectly positioned relative to each other for concatenated operationaccording to the invention to enhance convection of the electrolyte andthus accrue the benefits claimed of increased productivity and qualityof electrodeposited metal with higher current efficiency with a givencurrent density.

FIG. 5 is an elevation cross section of generic electrolytic cell (1)with the electrodes in working position together with the threesubsystems in their concatenated working positions. It shows the typicalpositioning in cell (1) of the cathodes (13) interleaved with anodes(14), and held distanced and in correct vertical position positivelyprevented from contact and electrical short circuits by means of twolateral edge vertical insulators (14 a) installed on the lateral edgesof opposite facing anodes (14). Lateral edge vertical insulators (14 a)also prevent metal electrodeposition on both lateral edges of thecathode (13). The cathodes (13) are installed in position in theindustrial cell by positive insertion of each cathode blank or mothersheet in the bottom slots formed in the distancing pyramids (12) of theelectrode distancing subsystem (10).

FIG. 6 is an isometric view of a preferred execution of the gas diffuserstructure in the convection enhancement Subsystem, in which themonolithic, self-supporting reticulated structure (6) encapsulating theisobaric rectangular loop (7) is replaced by a reticulated,self-supporting structure hermetically assembled with hollow structureshapes (60) of reinforced dielectric polymer composite materialwithstanding permanent immersion in acid electrolyte, where all therigidifying structural reticulation members are also hollow and areprovided with appropriate positive 100% gas tight connectors fordiffuser hoses, which are extremely important to properly diffuse themetered low volume of gas precisely and uniformly over the entire footprint of the cell bottom under the electrodes. Hollow self-supportingreticulated structure (60) is likewise abatable 110° from its normallyhorizontal working position, pivoting on basic structures (2) supportedon molded brackets (70) which are attached to one of the lateral longmembers as shown.

DETAILED DESCRIPTION OF THE INVENTION

Many aspects of the invention can be better understood with thereferences made to the drawings below. The components in the drawingsare not necessarily drawn to scale. Instead, emphasis is placed uponclearly illustrating the components of the present invention. Moreover,like reference numerals designate corresponding parts through theseveral views in the drawings.

In the description that follows, all specialty polymer compositematerials used are formulated according to U.S. Pat. No. 6,143,219 ofthe same inventor, and use only thermosetting polymer resins andconsequently, the polymer composite materials made according to thatpatent are also substantially gas occlusion-free and highly compactedmaterials of suitable structural, dielectric, and corrosion resistanceto withstand permanent 100% immersion in electrolyte that is required inthe described applications. Most ordinary thermoplastic polymers are notsuitable for this type heavy-duty service and simply cannot maintaintheir structural strengths and properties at operational temperatures.

A series of bases (4 are shown for the cell length shown, but it isenvisioned that there could be more or less depending on the desiredsize of the cell in operation) support structures (2) molded ofdielectric structural polymer composite materials withstanding corrosionfrom permanent immersion in electrolyte, assembled with transversestructural members (2B) and longitudinal structural members (2A) ofsimilar polymer composite materials forming a perfectly horizontal, flatand reticulated, rectangular structure, and are placed one after theother at a given design clearance height from the bottom of genericindustrial electrolytic cell (1), shown disposed for electrowinningcopper sheets (over stainless steel cathode blanks or otherwise motheror base copper sheets) from an electrolyte (100) containing ionizedcopper in acid solution, such base support structure (2) having verticalheight adjustment screws (3), for perfect horizontal leveling at thecorrect given design height clearance from the cell bottom to holdanodic slimes, and also horizontal lateral adjustment screws (4) forcentering the reticulated rectangular structure holding the gas bubblingdiffusers for electrolyte enhancement with respect to the center line ofthe cell and electrodes. The four base support structures (2) thuscorrectly installed constitute the basic or core system, which isdesigned ready to correctly support, position, and allow coordinatedfunctioning of the three subsystems, namely, the electrolyte pressurejetting feed system with the convection enhancing system, and bothpositioned correctly relative to the cell electrodes for optimal resultsby means of the electrode distancing system to maximize the electrolyticcell electrodeposition results through enhanced convection.

A subsystem for electrolyte pressure infeed into the industrial cell bymeans of twin manifolds with perforated parallel PVC (polyvinylchloride) or CPVC (chlorinated polyvinyl chloride) pipes (5) or (50)disposed at the lower portion of the lateral walls of genericelectrowinning or electrorefining electrolytic cell (1) installed incorrect positions, either shown as (5) or shown as (50), supportedhorizontally on the basic support structure (2) near the bottom and at agiven appropriate distance from the electrodes and the lateral walls inalternate positions (2C) in structure (2). The electrolyte feed pipes(5) or (50), are connected with the external electrolyte source throughdown corner feed pipe (5A) attached to the front wall of the cell (1).Orifices (5B) on longitudinal pipes (5) or (50) are each strategicallydistanced to jet electrolyte streams at given angles into each interelectrode space, and preferably, jet orifices are sized proportional todistance away from down corner so as to maintain substantially uniformjet flows emerging throughout the entire length of cell (1).

A subsystem for enhancing convection of the electrolyte is providedalternatively formed with a monolithic self-supporting, reticulatedstructure (6) preferably internally reinforced with fiber reinforcedplastic rebars (6A) molded with dielectric polymer material withstandingpermanent immersion in electrolyte, of rectangular shape and mountedhorizontally on the base support structure (2) previously installed atthe correct level in lower perimeter of the lateral and frontal walls ofgeneric cell (1). In fact, thermosetting polymers are mandatory for thistype of service as ordinary PVC and other thermoplastics simply do nothave the requisite durability for withstanding sustained immersion inhot (up to 65° C.) electrolyte. The reticulated structure (6) along itsentire outside perimeter encapsulates hollow structural shapes of highstrength, fiber reinforced structural polymer composite materials (7)hermetically assembled together forming a continuous hermetic isobaricrectangular loop (7) able to receive external gases at low pressurewithin the hollow interior of the shapes in the reticulated structure(6). The isobaric loop (7) feeds a closely monitored, predeterminedvolume flow of external gas—preferably air—to a plurality of parallelrows of elastomeric diffuser cylindrical elements, such as porous tubesshown as (9)—or preferably, each perforated in their lengths withappropriate orifices of given diameters at given distances from eachother in appropriate patterns. The preferred execution, however, is thereticulated, self-supporting structure hermetically assembled withhollow structural shapes (6) shown on FIG. 6, said hollow structuralshapes are formed in straight sections on solid mandrels and thenassembled with curved or T sections of structurally reinforced,dielectric polymer composite material withstanding permanent immersionin acid electrolyte, which can be made of appropriate thicknesses insuitable cross sections as needed structurally and to properly fit thecorrect flow and pressure drop of the diffuser elements used. Note: thatthe entire volume of the assembled reticulated hollow structure can bedesigned to provide as large an internal volume isobaric gas chamber asis convenient or needed, and, consequently, have available more finelycontrolled, efficient, and gentle gas feed suiting the type of thediffuser elements chosen for the appropriate sizes, density and/orpatterns of gas diffused bubbles needed. The diffuser elements (9) inturn, are mounted evenly spaced across the width and/or length of thegeneric electrolytic cell (1) held under or preferably over (not shown)the isobaric loop (7) from the reticulated structure (6) in holder barswith holding clips (not shown) (8) and respectively connectedlongitudinally—or transversally—either to the long or short sides, ofthe perimetral isobaric rectangular loop (7), to distribute givenpredetermined volumes at low pressures of air diffused in micro bubblesof given diameters in curtain or cloud patterns, as appropriate, intothe electrolyte, in a uniform and steady manner, from a horizontal planeat a given set distance from the lower edges of the electrodes. Tomaintain a stable and favorable bubbling configuration over a period oftime, it is essential to use 100% hermetic connectors to the diffusersin order to achieve and maintain satisfactory designed patterns likecurtains, clouds, scatter, etc. of uniform and stable micro bubbles inthe electrolyte at a given set flow of emerging gas at low pressurethrough all the given orifices in the diffuser elements. To obtain morediverse microbubble patterns and also tighter control of microbubblediameter uniformity and stability using low gas volumes and lowpressure, hollow structure (60) is definitely the better choice. Thepresent invention incorporates the discovery of the phenomena andseveral unanticipated results of introducing low volume, low-pressuregas bubbling in industrial cells. Conclusively, first and foremost, thatit is not so much the volume nor the pressure of gas bubbled as theeffectiveness of the spatial geometrical configuration of the convectionenhancing system relative to the electrodes, on one hand and matchingthe characteristics of the chosen or given electrolyte infeed system onthe other, plus the availability of specific and precise fluidadjustments that are steady in time for which the electrolyte convectionenhancement gas system used is designed so as to effectively distributeconstant, uniform and steady metered diffused gas volumes at minimumpressure throughout a horizontal plane that are correctly located underthe foot print of the vertically hanging electrodes of the industrialcell that determines the overall effectiveness and good quality results.

It was discovered that using reticulated structure (6) with isobaricloop, the longitudinal disposition of gas diffuser means (as inPCT—WO2005/019502 A1 of March, 2005) parallel to the industrialelectrolytic cell length dimension are much slower to react andstabilize with a given gas volume and pressure, and therefore theyproduce uneven or unsteady results in quality of electrodeposition,especially in cases when there are frequent interruptions to theconstant gas supply. The transverse disposition of diffuser meansrelative to the cell length (preferred orientation in the art per someU.S. Patents reviewed) is very responsive instead, easier to adjust thepattern desired and evidences more stable favorable electrodepositionresults. It is further discovered that it takes time (transversediffusers orientation is faster and hollow isobaric structure (60) evenfaster) for the two systems working interlinked to achieve effective andstable patterns of flow. Essentially, the curtains, clouds, or scatterof diffused gas micro bubbles as they emerge into the electrolyte minglewith the electrolyte, which is already generally in ascending movementsby virtue of its pressurized and directed jet infeed of electrolyte, andthe apparent resulting local density reduction in the electrolyte byvirtue of the gas microbubbles that provide air lift and spin in afavorable ascending, mild turbulent wiping movement very close to thecathode faces—just kissing or touching the electrode surfaces. Favorableconvection enhancing wiping movement, as used previously andhereinafter, is shown by arrows 100A that convey a generally upwardmovement across the surface of the electrode, similar to the upwardmovement of an automobile windshield wiper. It is this latter subtleraction achieved with sufficiently abundant microbubbles at low pressurewhich intensifies the convection in the bulk electrolyte in theinterelectrode spaces, adding buoyancy to first imparted convection bythe emerging jets under pressure from the electrolyte infeed subsystem(5) below, that imparts critical effectiveness. This subtler action isenhanced with more abundant, finer microbubbles—substantially all under2 mm in diameter—easily obtained and sustained using the hollowstructure (60). It was discovered unexpectedly that, contrary to priorart, substantially lower volumes of sparged gas and at very lowpressures suffice to enhance original convection by imparting the verydesirable gentle kissing turbulence at the cathode surfaces at a givencurrent density. It was also verified through measurements in anindustrial electrowinning environment that using lower volumes of gasand at minimum pressures for convection in the electrolytic cellspositively do not contribute to generation of acid mist; quite thecontrary, diffused air microbubbles appeared to diminish misting perhapsby dissolving some of the oxygen bubbles generated in the anode surfacesthat are the cause and principal source of acid mist in electrowinning.The abatement of acid mist seems to be more effective with abundantcloud patterns of very fine microbubbles produced using hollow structure(60). In order to achieve the localized gentle kissing turbulence at theplating surfaces, not only does the diffusion of the emerging gasrequire even distribution throughout the electrolyte in the cell, butalso meticulously adjusted to the pressurized infeed volume rate ofelectrolyte containing the plating ion species, so that the combinedeffect of gas and electrolyte infeed throughout the entire horizontalplane foot print of electrodes in the cell is stable enough in time toevenly distribute and homogenize the available concentration of the ionmetal species, starting at a correct predetermined distance under thevertically hanging electrodes, so they are abundantly available forplating on the full cathodes surfaces up above. It is the propercombination of contributions from both the electrolyte jet infeed systemplus the electrolyte enhancement system—particularly executed withhollow reticulated structure—in this invention that are the keys toachieve consistent, repeatable overall optimum electrolyte convection,resulting in uniform an sustained optimum quality electrodeposition.Generally, electrolyte volume flows in electrolytic cells are determinedby chemical and mass transfer considerations and total available platingsurface for a given current density, as discussed earlier and isgenerally referred as specific flow of the industrial cell. Appropriatelow pressure gas volume flows are essentially established relative tothe selected electrolyte specific volume flow into the industrial cell,choosing the lowest possible pressure drop diffuser elements so that thepressure in the system will be the lowest necessary to overcome theelectrolyte hydraulic column and the pressure drop across the diffusersthemselves and still produce stable microbubbles—all preferably under 4mm in diameter—in uniform patterns. The harmonious, combined resultinside the industrial cell—of pressure electrolyte feed combined withthe steady low pressure/low volume gas bubbling enhancement of thisinvention—effectively diminishes the thickness of the diffusion layer atthe electrode surfaces, and quite importantly also, enhances uniformdistribution of the given current density throughout the cathodesurfaces and uniform mass transfer of the plating ions species, bothessential conditions for controlled, uniform growth of the cathodecopper metal plates without pores and with uniform thickness throughout.It was discovered after repeated monitored trials that it is thesuperposition of these combined convection effects that principallypromotes more homogeneous and steady copper ion mass transfer to theentire surfaces of the cathodes, ultimately resulting in substantiallyuniform, non porous, substantially free from deposited impurities, highdensity copper electrodeposition, flat and smooth metal platingthroughout the cathode surfaces which is also faster and thereforeproceeds with higher current efficiency. All prior art gas bubblingsystems reviewed claim the use of at least twice the pressure and morethan twice the gas volume flow than the amounts for good quality resultsdisclosed in present invention. By using the correct combination of gaspressure under 1000 Nmbar and gas volume under 120 Nl/min in anindustrial electrolytic cell of specific flow between approximately 0.10and 0.20 cubic meter/hour/square meter of cathodic plating surface, theoverall bulk electrolyte enhanced convection movement (100 a) startingfrom below the foot prints of interelectrode spaces in the cell—as shownin FIG. 2. The electrolyte is accelerated and directed upwards from thehorizontal plane parallel—and at a given distance—from the cell bottomwith the incoming jet flows (5B) from the infeed electrolyte piping (5)or (50) on support structure (2), passing through the curtains or cloudsof gas bubbles emerging from low pressure drop diffusers in the bottomor preferably top (not shown) of reticulated structure (6) in the cell(1), directed generally in an upward direction and with predeterminedpattern which will sweep with gentle and slow turbulence (of Reynoldsnumber under 1000 in electrowinning) the entire faces of the electrodesin their ascending movement towards the surface of the electrolytedirected as shown (100 a) towards the upper vertices of the electrodes,and then, beginning their vertical descent towards the bottom of thecell through the downward convection channels which is formed at bothsides of the cell, as established by the lateral walls and the laterallyenclosed electrodes, with their interspaces restricted laterally bytheir distancing insulators (13 a). The relatively slow speed of theelectrolyte volume moving down is accelerated in passing by therestricted width of the side downward channels and the electrolytestrikes baffles (11) of the electrode distancing system (10) creating anelectrolyte eddy discharging towards the electrode's interspaces andtowards the bottom of the cell. The eddies at baffles (11) tend to causeheavier slime particles in suspension to loose their kinetic energy anddeposit on the surfaces of baffles (11) from where they gently fall offtowards the cell bottom (200) and accumulate for periodic removal.

A subsystem for positively distancing the electrodes (10) that holds theanodes and cathodes from their bottom edges at all times is formed bytwo horizontal parallel solid channel structural shapes mounted uprighton the cell bottom near the lateral walls of the cell (1), molded usinghigh impact strength, dielectric polymer and/or elastomeric polymercomposite materials withstanding corrosion of permanent immersion inelectrolyte. The solid horizontal channels (10) are molded of one pieceeach and run perfectly parallel the full length of the cell (1),mounted—as shown in FIGS. 1 and 4—on top of their respective basesupport structures (2) duly centered longitudinally and transverselywith respect to the cell (1) at the correct position with dovetails(10A). Channel structural shapes (10) hold distancing pyramids (12)which are molded with high impact polymer elastomeric materialswithstanding corrosion of permanent immersion in electrolyte, designedto hold vertically in place near their lateral vertices the anodes andcathodes, their correct locations and given spacing of anodes andcathodes intercalated at their lower edges. In order to maintain theproper horizontal spacing distance and maintain the intercalatedelectrodes at all times positively insulated from each other, thevertical edges of the anodes are fitted with two parallel distancinginsulator channels (13 a) which prevent contact—and electric shortcircuits—with the cathodes in the cell when the electrodes areinstalled, and particularly when the cathodes are harvested and removedfrom the cell with the anodes remaining in the cell fully energized.Another complementary function of distancing insulator channels (13 a)is providing an electric shield along the vertical edges of permanentcathodes so when they are energized and immersed in the electrolyte;they remain free of localized copper deposit along both vertical edges.This is very significant because upon harvesting from the cell, havingthe cathode blank edges free of copper deposit facilitates the strippingof the full copper plates deposited from both opposite surfaces of thepermanent cathode blanks. Distancing pyramids shown (12) are fitted intothe channel support structures (10) by sliding each into correctposition under the vertical hanging intercalated cathodes/anodes andfixed in correct locations from the ends of each channel supportstructure (10) with set screws (not shown). Another important functionof the pyramids (12) and baffles (11) in this subsystem is that theyserve as sacrificial impact deflectors/protectors from eventualcatastrophic impacts on the convection intensifying subsystem by theaccidental fall of full cathodes, particularly from mother plates orsoluble anodes in electrorefining industrial cells.

It should be understood that while the preferred embodiments of theinvention are described in some detail herein are pertinent to theoperation of an industrial copper electrowinning cell, the presentdisclosure is made by way of example only and that suitable variationsand changes thereto are introduced for use in copper electrorefining andfor use in electrodeposition processes of non ferrous metals withoutdeparting from the subject matter coming within the scope of thefollowing claims, and a reasonable equivalency thereof, which claims Iregard as my invention.

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

1. A system for electrodeposition of non ferrous metals comprising anoperating electrolytic industrial cell with appropriate cathodes andanodes, and a given flow of an electrolyte composition and currentdensity; a leveled and aligned horizontal support structure orindividual supports correctly installed inside the cell in favorableposition relative to the electrodes; a means of electrolyte infeed,where the means of electrolyte infeed allows discharge of theelectrolyte relative to the electrodes and is aligned and leveled fromthe leveled and aligned horizontal support structure or individualsupports; a means of enhancing convection, where the means of enhancingconvection is supported from the leveled and aligned horizontal supportstructure or individual supports; and a means of positively distancingelectrodes, where the means positively distancing electrodes issupported from the leveled and aligned horizontal support structure orindividual supports.
 2. The system of claim 1, wherein leveled andaligned horizontal support structure or individual supports comprisesdielectric structural polymer composite materials.
 3. The system ofclaim 1, wherein the leveled and aligned horizontal support structure orindividual supports comprise a means of vertical height adjustment. 4.The system of claim 1, wherein the leveled and aligned horizontalsupport structure or individual supports comprises a means of horizontallateral adjustment.
 5. The system of claim 1, wherein the means ofelectrolyte infeed comprises electrolyte feed pipes.
 6. The system ofclaim 5, wherein the electrolyte feed pipes are twin manifolds withperforated parallel PVC or CPVC pipes.
 7. The system of claim 5, whereinthe electrolyte feed pipes comprise a plurality of orifices to jetelectrolyte streams at given angles into each interelectrode space. 8.The system of claim 1, wherein the means of enhancing convection is acontinuous hermetic isobaric structurally self supporting loop, wherethe continuous hermetic isobaric loop comprises gas diffuser elementsand gas hermetic connectors.
 9. The system of claim 1, wherein the meansof positively distancing electrodes horizontally comprises structuralshapes under the electrodes.
 10. The system of claim 9, wherein themeans of positively distancing electrodes at their given distanceshorizontally further comprises distancing pyramids, where the distancepyramids are held at precise positions by the solid channel structuralshapes.
 11. A method of electrodeposition of non ferrous metalscomprising the steps of obtaining an industrial electrolytic cell withvertically intercalated planar electrodes and appropriate infeed ofelectrolyte of given composition operated at a given current densitylocating individual supports or a support structure precisely inside thecell, a means of electrolyte infeed, a means of enhancing convention,and a means of positively distancing electrodes horizontally and/orvertically, supporting the means of electrolyte infeed, the means ofenhancing convention, and the means of positively distancing electrodesat correct locations relative to each other by individual supports or asupport structure, using at least the means of electrolyte infeed andthe means of enhancing convention, and also the means of positivelydistancing electrodes, all concatenated to achieve desired qualitydeposit of non ferrous metals on cathode plate electrodes.
 12. Themethod of claim 11, wherein the quality deposit of non ferrous metals isan electrowinning process.
 13. The method of claim 11, wherein thequality deposit of non ferrous metals is an electrorefining process. 14.The method of claim 11, wherein the means of enhancing convection iscomprised of a continuous gas hermetic isobaric loop, where thecontinuous hermetic isobaric loop comprises gas hermetic connectors anddiffuser elements.
 15. The method of claim 14, wherein the continuoushermetic isobaric structure receives external gases at low pressure anddistributes the gases uniformly to chosen diffusers to generate bubblesof appropriate size, density and appropriate diffusion patterns thatenhance convection and improve the quality of deposition of non ferrousmetals and improve process productivity.
 16. The method of claim 15,wherein the external gases are at a pressure of under 1000 Nmbar. 17.The method of claim 15, where the cathode plate electrodes have aplating surface, wherein the specific flow of electrolyte is betweenapproximately 0.10 and 0.20 cubic meter/hour/square meter of cathodicplating surface in each electrolytic cell.
 18. The method of claim 15,wherein the bubbles are less than 4 mm in diameter generated bydiffusers able to diffuse up to 120 It/min/cell of air flow at maximum1000 Nmbar pressure.
 19. An apparatus for electrodeposition of nonferrous metals comprising an industrial electrolytic cell withvertically intercalated electrodes, given flow of appropriateelectrolyte of given composition operated at a given current density, asupport structure, electrolyte feed pipes, a reticulated gas diffusingstructure, and solid horizontal channels; where the electrolyte feedpipes are twin manifolds with perforated parallel PVC or CPVC pipes,where the reticulated structure is hermetically assembled to form acontinuous hermetic isobaric rectangular loop, where the solidhorizontal channels support anodes and cathodes, and where the supportstructure supports the electrolyte feed pipes, the reticulatedstructure, and the solid horizontal channels.
 20. The apparatus of claim19, wherein the continuous hermetic isobaric rectangular loop comprisesgas hermetic connectors and diffuser elements.